Adjust nodeFunctionscan.c to reset transient memory context between calls

to the table function, thus preventing memory leakage accumulation across
calls.  This means that SRFs need to be careful to distinguish permanent
and local storage; adjust code and documentation accordingly.  Patch by
Joe Conway, very minor tweaks by Tom Lane.

1 files changed, 23 insertions, 55 deletions

diff --git a/contrib/pgstattuple/pgstattuple.c b/contrib/pgstattuple/pgstattuple.c
index a357f6f412a..4fbc60bcf2a 100644
--- a/contrib/pgstattuple/pgstattuple.c
+++ b/contrib/pgstattuple/pgstattuple.c
@@ -1,5 +1,5 @@
 /*
- * $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.7 2002/08/23 08:19:49 ishii Exp $
+ * $Header: /cvsroot/pgsql/contrib/pgstattuple/pgstattuple.c,v 1.8 2002/08/29 17:14:31 tgl Exp $
  *
  * Copyright (c) 2001,2002  Tatsuo Ishii
  *
@@ -25,10 +25,10 @@
 #include "postgres.h"
 
 #include "fmgr.h"
+#include "funcapi.h"
 #include "access/heapam.h"
 #include "access/transam.h"
 #include "catalog/namespace.h"
-#include "funcapi.h"
 #include "utils/builtins.h"
 
 
@@ -41,19 +41,19 @@ extern Datum pgstattuple(PG_FUNCTION_ARGS);
  * returns live/dead tuples info
  *
  * C FUNCTION definition
- * pgstattuple(TEXT) returns setof pgstattuple_view
- * see pgstattuple.sql for pgstattuple_view
+ * pgstattuple(text) returns pgstattuple_type
+ * see pgstattuple.sql for pgstattuple_type
  * ----------
  */
 
-#define DUMMY_TUPLE "pgstattuple_view"
+#define DUMMY_TUPLE "pgstattuple_type"
 #define NCOLUMNS 9
 #define NCHARS 32
 
 Datum
 pgstattuple(PG_FUNCTION_ARGS)
 {
-	text	   *relname;
+	text	   *relname = PG_GETARG_TEXT_P(0);
 	RangeVar   *relrv;
 	Relation	rel;
 	HeapScanDesc scan;
@@ -71,62 +71,30 @@ pgstattuple(PG_FUNCTION_ARGS)
 	double		dead_tuple_percent;
 	uint64		free_space = 0; /* free/reusable space in bytes */
 	double		free_percent;	/* free/reusable space in % */
-
-	FuncCallContext	   *funcctx;
-	int					call_cntr;
-	int					max_calls;
 	TupleDesc			tupdesc;
 	TupleTableSlot	   *slot;
 	AttInMetadata	   *attinmeta;
+	char			  **values;
+	int					i;
+	Datum				result;
 
-	char **values;
-	int i;
-	Datum		result;
-
-	/* stuff done only on the first call of the function */
-	if(SRF_IS_FIRSTCALL())
-	{
-		/* create a function context for cross-call persistence */
-		funcctx = SRF_FIRSTCALL_INIT();
-    
-		/* total number of tuples to be returned */
-		funcctx->max_calls = 1;
-    
-		/*
-		 * Build a tuple description for a pgstattupe_view tuple
-		 */
-		tupdesc = RelationNameGetTupleDesc(DUMMY_TUPLE);
-    
-		/* allocate a slot for a tuple with this tupdesc */
-		slot = TupleDescGetSlot(tupdesc);
-    
-		/* assign slot to function context */
-		funcctx->slot = slot;
-    
-		/*
-		 * Generate attribute metadata needed later to produce tuples from raw
-		 * C strings
-		 */
-		attinmeta = TupleDescGetAttInMetadata(tupdesc);
-		funcctx->attinmeta = attinmeta;
-	}
+	/*
+	 * Build a tuple description for a pgstattupe_type tuple
+	 */
+	tupdesc = RelationNameGetTupleDesc(DUMMY_TUPLE);
 
-	/* stuff done on every call of the function */
-	funcctx = SRF_PERCALL_SETUP();
-	call_cntr = funcctx->call_cntr;
-	max_calls = funcctx->max_calls;
-	slot = funcctx->slot;
-	attinmeta = funcctx->attinmeta;
+	/* allocate a slot for a tuple with this tupdesc */
+	slot = TupleDescGetSlot(tupdesc);
 
-	/* Are we done? */
-	if (call_cntr >= max_calls)
-	{
-		SRF_RETURN_DONE(funcctx);
-	}
+	/*
+	 * Generate attribute metadata needed later to produce tuples from raw
+	 * C strings
+	 */
+	attinmeta = TupleDescGetAttInMetadata(tupdesc);
 
 	/* open relation */
-	relname = PG_GETARG_TEXT_P(0);
-	relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,"pgstattuple"));
+	relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,
+															 "pgstattuple"));
 	rel = heap_openrv(relrv, AccessShareLock);
 
 	nblocks = RelationGetNumberOfBlocks(rel);
@@ -223,5 +191,5 @@ pgstattuple(PG_FUNCTION_ARGS)
 	}
 	pfree(values);
     
-	SRF_RETURN_NEXT(funcctx, result);
+	PG_RETURN_DATUM(result);
 }